This invention relates generally to tuners, and more particularly, to a combined UHF and VHF television tuner utilizing a single selector shaft for selecting all of the 82 UHF and VHF television channels, a single fine tuning shaft and a single indicator for displaying each of the individual UHF and VHF channel numbers.
Several combined UHF and VHF television tuners are known. In certain prior art combination tuners, two separate selector shafts, one for selecting the UHF channels and the other for selecting the VHF channels, are used. In other such tuners a single selector shaft is employed for selecting channels in both the UHF and VHF bands. Both memory and non-memory type fine tuning mechanisms have been used, and single and multiple fine tuning shafts have been utilized for driving the fine tuning mechanisms. In addition, both single and multiple indicators have been employed to display the number of the channel selected by the appropriate selector shaft.
Whereas these tuners provide a way to select both UHF and VHF television channels, the use of multiple selector and fine tuning shafts is not entirely satisfactory because it results in an inconvenience to the user when switching between UHF and VHF bands. In addition, the operation and feel of the two tuning shafts is generally sufficiently different that the user has to learn two different tuning techniques for tuning the channels from the two different bands. The use of two separate tuning shafts also usually requires the use of two separate channel indicators, because the use of a single indicator controlled by two separate shafts would tend to confuse the operator as to which of the selector shafts to turn to obtain a change in channels. In the alternative, a complex and expensive switching and lighting arrangement is required to inform the operator which turning shaft is being displayed. Also, the Federal Communications Commission requirement that UHF tuners be compatible in all respects with VHF tuners must be met, preferably without materially increasing the overall cost of the combination tuner.
Combination tuners utilizing a single selector shaft have generally been provided with a predetermined, relatively small number of UHF positions for selecting preselected ones of the UHF channels. The aforementioned UHF positions may be interleaved between the VHF positions or may be positioned at one end of the tuning range. While such an approach does simplify the tuning procedure, it requires the customer to add on a tag or label indicating the channel numbers of the television stations the user wishes to receive in his area if a unique channel number indication is to be provided as the UHF stations are selected. Also, with such an approach the number of available UHF positions is limited, thereby limiting the number of UHF stations that can be selected. Furthermore, the UHF channel positions are not generally arranged in a continuous numerical sequence of channel numbers, particularly when the interleaved UHF and VHF approach is used.
Accordingly, it is an object of the present invention to provide a new and improved combination UHF and VHF tuner.
It is yet another object of the present invention to provide a combined UHF and VHF tuner having a single detented selector shaft capable of uniquely and sequentially selecting each channel in both of the UHF and VHF bands.
Another object of the present invention is to provide an improved combination UHF and VHF television tuner wherein the tuning of the UHF and VHF bands is operationally so similar that both the UHF and VHF channels may be selected by an operator using a single tuning technique.
Still another object of the present invention is to provide an improved combination UHF and VHF television tuner having a channel indicator that sequentially displays a unique channel number for each station in the UHF band and each station in the VHF band.
A further object of the present invention is to provide an improved UHF and VHF television tuner utilizing a single fine tuning shaft for memory fine tuning both the UHF and VHF channels.
In accordance with a preferred embodiment of the invention, a continuously tunable UHF tuner is provided with a detenting mechanism and a detented selector shaft for rendering the UHF tuner incrementally tunable between detent positions with each detent position corresponding to a single distinct UHF television channel, thereby making the tuner of the UHF tuner similar to that of a standard VHF tuner.
A standard detented VHF tuner is mounted adjacent to the UHF tuner, and a gear mechanism is utilized to couple the selector shaft and the tuning shaft of the VHF tuner to permit the VHF tuner to be driven by the same selector shaft that drives the UHF tuner. A disengaging mechanism responsive to the position of the selector shaft is utilized to disengage the gear mechanism to decouple the VHF tuner from the selector shaft when the common selector shaft is rotated into the UHF range.
The UHF tuner is provided with a plurality of cams disposed about a rotatable turret for providing a memory type fine tuning in the UHF band. A single fine tuning shaft is coupled to a second gear mechanism for selectively engaging the UHF fine tuning cams and the fine tuning elements of the VHF tuner. A lock out mechanism is provided in the fine tuning mechanism so that only the VHF tuner is tuned when the selector shaft is positioned to receive one of the VHF channels. Finally, apparatus is provided for reducing the effects of the UHF detenting mechanism when VHF channels are being selected to maintain the "feel" of the selector shaft substantially the same regardless of whether a UHF or a VHF channel is being selected.